Polyurethane polymers are conventionally prepared by the reaction of an organic polyol or polyether polyol with an organic polyisocyanate. It is conventional to produce a polyether polyol to be used in manufacturing polyurethane polymers from sugars. Sucrose is frequently used for this purpose because of its availability and low cost. Lactose from whey has been shown to be usable in making polyurethane foams. See Richardson et al, U.S. Pat. Nos. 3,629,162 and 3,658,731. However, lactose undergoes side reactions when heated under basic conditions, as must be done as part of the synthesis of a polyether polyol therefrom. The reaction products include compounds that make the polyether polyol dark in color, leading to dark polymer preparations unsuitable for many applications.
Foamed polyurethane polymers are widely used for various purposes. A disadvantage of such polyurethane foams is their flammability. It is necessary to add compounds of phosphorus, halogen containing compounds, or other materials to cause the foams to be self-extinguishing or non-burning. Urea has been mechanically mixed with polyurethane foams to produce a self-extinguishing foam. Hesskamp, U.S. Pat. No. 3,717,597 discloses a self-extinguishing composite material including bits of polyurethane foam mechanically mixed with urea and bound together to form a self-extinguishing, composite material. However, difficulties have been encountered when attempts have been made to incorporate granular urea in polyurethane foams by mechanically mixing it with a conventional polyol prior to use of the polyol. When it is necessary to move the liquid polyol and dispersed granular urea through pumps, pipes, nozzles, and the like, the urea increases the likelihood of the system stopping up and leads to abrasion and increased wear of such parts as pumps and nozzles.
Reymore, et al., U.S. Pat. No. 3,420,787 teaches a process for producing fire-retardant polyurethanes by incorporating in the polymerization reaction mixture a substituted urea having the formula ##STR1## wherein Ar represents an aromatic hydrocarbon residue having a valancy n which is substituted by from 0 to 4 halogen atoms, R.sub.1 and R.sub.2 each represent lower-hydroxyalkyls, and n is an integer from 1 to 3, inclusive. Richter, et al., U.S. Pat. No. 4,154,931 discloses the preparation of cyclic ureas declared to be useful as cross-linkers and extenders in polyurethane formulations, although their effect on flammability is not disclosed. For the most part, such materials and other conventional flame retardants are relatively expensive, increasing the cost of fire resistant polyurethane polymers. Antimony oxide powder is a less expensive but still effective fire retardant when mixed through the bulk of a polyurethane foam. However, loose particles of the antimony oxide render the foam powdery, which is an unsatisfactory quality in many applications.